Homo- and heteroleptic group 4 2-(diphenylphosphino)pyrrolide complexes: Synthesis, coordination chemistry and solution state dynamics

The synthesis and solid state structures of homo- and heteroleptic Zr and Ti complexes of 2-(diphenylphosphino)pyrrolide (NP) are reported. The homoleptic Zr(NP)4 (1) and Ti(NP)4 (2) are 8-coordinate in the solid state, and both show extremely long M–P bonds of approximately 2.9 A. In solution, the phosphine ligands in all complexes are labile: in the titanium complexes phosphine dissociation is rapid at room temperature and equilibrates all phosphines into a single 31P resonance, whereas in the Zr complex 1 dissociation is slower and full equilibration does not occur until 90 °C. The potential to utilize these novel complexes as metalloligands toward other transition metals is discussed.